Frequency and location of microbleeds in patients with primary intracerebral hemorrhage.

BACKGROUND AND PURPOSE: MRI is known to detect clinically silent microbleeds (MBs) in patients with primary intracerebral hemorrhage (pICH), but the frequency and diagnostic and clinical significance of this finding are still debated. Therefore, we investigated a consecutive series of pICH patients and analyzed the patterns of MB distribution in the context of clinical variables and location of the symptomatic hematoma. METHODS: The study population consisted of 109 patients with pICH. There were 59 women and 50 men aged 22 to 91 years (mean 64.6 years). MRI was obtained on a 1.5-T system with use of a gradient-echo T2*-weighted sequence. A cohort of 280 community-dwelling asymptomatic elderly individuals who underwent the same imaging protocol served for comparison. RESULTS: MBs were seen in 59 (54%) patients and ranged in number from 1 to 90 lesions (mean 14, median 6). In the majority of patients, MBs were located simultaneously in various parts of the brain, with a preference for cortical-subcortical regions (39%) and the basal ganglia/thalami (38%). There was some tendency toward a regional association between MB location and the site of the symptomatic hematoma, but we could not discern specific patterns of MB distribution. Logistic regression analysis identified MBs, periventricular hyperintensity grades, and lacunes but not risk factors as independent variables contributing to a correct classification of pICH and control individuals. CONCLUSIONS: MBs can be detected in more than half of the patients with pICH and appear to be quite general markers of various types of bleeding-prone microangiopathy.

Histopathologic analysis of foci of signal loss on gradient-echo T2*-weighted MR images in patients with spontaneous intracerebral hemorrhage: evidence of microangiopathy-related microbleeds.

BACKGROUND AND PURPOSE: Patients with spontaneous intracerebral hemorrhage (ICH) frequently have small areas of signal loss on gradient-echo T2*-weighted MR images, which have been suggested to represent remnants of previous microbleeds. Our aim was to provide histopathologic support for this assumption and to clarify whether the presence and location of microbleeds were associated with microangiopathy. METHODS: We performed MR imaging and correlative histopathologic examination in 11 formalin-fixed brains of patients who had died of an ICH (age range, 45-90 years). RESULTS: Focal areas of signal loss on MR images were noted in seven brains. They were seen in a corticosubcortical location in six brains, in the basal ganglia/thalami in five, and infratentorially in three specimens. Histopathologic examination showed focal hemosiderin deposition in 21 of 34 areas of MR signal loss. No other corresponding abnormalities were found; however, hemosiderin deposits were noted without MR signal changes in two brains. All specimens with MR foci of signal loss showed moderate to severe fibrohyalinosis, and there was additional evidence of amyloid angiopathy in two of those brains. CONCLUSION: Small areas of signal loss on gradient echo T2*-weighted images indicate previous extravasation of blood and are related to bleeding-prone microangiopathy of different origins.